| Currently the most popular adhesives applied to FPC industry are two categories modified acrylic and modified epoxy resins. Modified acrylate adhesives are environmental protection, cheap and small resin flow. However, they have undesirably poor weather ability, low thermal stability, high moisture absorption, unsatisfactory dimension stability, to easy to blister in curing stage, limited their application in FPC industry. Benzoxazine resin is a kind of novel phenolic resin. Nitrogen network similarities to phenolic formed by ring-opening curing reaction under the heat or catalysts. They retain those good properties of phenolic resin, such as cheap, fine hardness, good at thermal stability, flame-retardant properties and electrical insulating ability and so on, while have high Tg, good flexibility and small-shrinkage. Benzoxazine can be modified acrylic adhesive to overcome the disadvantages mentioned above, to obtain a new adhesive with high performance.Modified acrylate adhesives were prepared through blending by colloid mill with benzoxazine as modifier, corresponding flexible printed circuit base material (also called flexible copper clad laminate, FCCL) also be prepared. The properties of modified adhesives and FCCL were studied in this paper, and identified the best prescription of modified adhesives and Productive Process of FCCL.A series of acrylic emulsion was synthesized by pre-emulsified and half-continued emulsion polymerizing. The optimal formulation of acrylic emulsion determined by investigation of solid content, gelling rate and water absorption were as follow: the weight ratio of soft and hard monomer was 3:1; functional monomer content was 5%~6% of total monomer; emulsifier was SLS+OP-10+SDS (mass ratio of OP-10 and SDS was 2:1, adding together); mass ratio of initiator was 0.5%.Modified acrylate adhesives were prepared through blending with benzoxazine and other Components by colloid mill. The effects of the type and amount on properties of modified adhesives and FCCL, and the influence of hot-press technology on properties of the peel strength of FCCL were studied.The curing process of modified adhesives and the preparation technology of FCCL have been studied carefully. The curing reaction of BOZ/PA adhesives has been studied by non-isothermal DSC; the results indicated that curing activation energy and temperature of the biggest thermal releasing peaks of the BOZ/PA adhesives decreased with the addition of BOZ content. The apparent activation energy values of BOZ/PA adhesives with BOZ content of 5wt%,10wt% and 20wt% obtained by Kissinger treatment are equal to 28.60,28.27,19.82kJ/mol,respectively. The curing reaction is easier because of additional of BOZ content. Temperature, time and pressure have important effects on the mechanical properties of BOZ/PA FCCL. The proper technology condition for FCCL production as follows: latex coated PET film was made by dry 10min at 115℃; plastic-envelop machine temperature of adhesives film transfer is 130℃and agglutinating copper foil is 120℃; complex copper foil pretreatment of 160℃about 1h; hot-press 50min at 190℃and 4MPa; post-treatment 2h at 250℃vacuum oven. The IR of adhesive before and after curing reaction also validates the rationality of the curing technology. |
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